Wellington's April 27 thermal maxima will not breach 16°C. Current ensemble forecasts indicate high certainty of a deepening Tasman Sea trough driving cooler, post-frontal airmasses over the North Island. Without robust warm advection from a northerly component or strong anticyclonic ridging, the daily lapse rate will suppress surface temperatures. Historical analogues for late April reinforce a declining seasonal temperature trend, making 16°C an aggressive threshold under the projected synoptic setup. 90% NO — invalid if a strong, persistent northerly flow develops.
